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authorDan Carpenter <dan.carpenter@oracle.com>2017-09-22 23:43:25 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-09-25 11:57:13 +0300
commit57999d1107c1e60c2ca7088f2ac0f819e2f554b3 (patch)
tree6081b8b694eeae7c08ea2cc082c9966517cdb838 /drivers/usb
parent1fbbb78f25d1291274f320462bf6908906f538db (diff)
downloadlinux-57999d1107c1e60c2ca7088f2ac0f819e2f554b3.tar.xz
USB: devio: Prevent integer overflow in proc_do_submiturb()
There used to be an integer overflow check in proc_do_submiturb() but we removed it. It turns out that it's still required. The uurb->buffer_length variable is a signed integer and it's controlled by the user. It can lead to an integer overflow when we do: num_sgs = DIV_ROUND_UP(uurb->buffer_length, USB_SG_SIZE); If we strip away the macro then that line looks like this: num_sgs = (uurb->buffer_length + USB_SG_SIZE - 1) / USB_SG_SIZE; ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ It's the first addition which can overflow. Fixes: 1129d270cbfb ("USB: Increase usbfs transfer limit") Cc: stable <stable@vger.kernel.org> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Acked-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/usb')
-rw-r--r--drivers/usb/core/devio.c5
1 files changed, 5 insertions, 0 deletions
diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c
index 318bb3b96687..e9326f31db8d 100644
--- a/drivers/usb/core/devio.c
+++ b/drivers/usb/core/devio.c
@@ -140,6 +140,9 @@ module_param(usbfs_memory_mb, uint, 0644);
MODULE_PARM_DESC(usbfs_memory_mb,
"maximum MB allowed for usbfs buffers (0 = no limit)");
+/* Hard limit, necessary to avoid arithmetic overflow */
+#define USBFS_XFER_MAX (UINT_MAX / 2 - 1000000)
+
static atomic64_t usbfs_memory_usage; /* Total memory currently allocated */
/* Check whether it's okay to allocate more memory for a transfer */
@@ -1460,6 +1463,8 @@ static int proc_do_submiturb(struct usb_dev_state *ps, struct usbdevfs_urb *uurb
USBDEVFS_URB_ZERO_PACKET |
USBDEVFS_URB_NO_INTERRUPT))
return -EINVAL;
+ if ((unsigned int)uurb->buffer_length >= USBFS_XFER_MAX)
+ return -EINVAL;
if (uurb->buffer_length > 0 && !uurb->buffer)
return -EINVAL;
if (!(uurb->type == USBDEVFS_URB_TYPE_CONTROL &&